Results from spine-tuned arrows
#1
Thread Starter
Join Date: Feb 2003
Location:
Posts: 2,413

This is related to the post where I described a spine tester that I built. To test the value of spine-tuned arrows, I fletched a dozen Gold Tip Hunters 7595 and shot them at various distances with 125 gr. 2-blade Magnus Stingers. I decided on these lower priced carbons, which are reputed to have poor spine consistency.
I asked for input on what an acceptable spine variance would be, and didn't get an answer yet, so I decided to test some of the arrows that had more variance than the others. I choose five arrows where the weakest and strongest sides were between .008 and .015 difference. I have no idea if this falls in a good or bad range, but I figured these were no better than average for a dozen GT hunters. Out of the dozen, there were 6 other arrows that measured more consistant than these and one that measured much worse.
After testing with the spine tester, I marked the weak side of each arrow and placed the cock fletch on that mark. I used 4" feathers attached with a helical clamp. Draw weight was 65 lbs out of a hybrid cam bow. Draw length was 28.5" and arrow length was 28.75". The bow was well-tuned and shooting field tips very well if I did my part. A whisker biscut was used as the rest. A mechanical release was used. I shot the 5 arrows with the Stingers attached, at broadhead targets set at 20, 40 and 60 yards. The arrows were shot one at a time and then marked. I wanted to determine group size and location without actually shooting a group. A total of 3 groups were shot at each distance and averaged to determine group size and location.
To start, no tuning adjustments were made and the sight was not adjusted. At 20 and 40 yards I could tell no difference in group location between these arrow and my field tipped arrows. The sight needed absolutely no adjustment and no tuning adjustments were made either. The group size at these distances was actually a bit smaller than my normal field tip group. It is likely I was just having a good day shooting, but all five arrows flew nicely into the group. Normally, I'd shoot a dozen, culling them down to the best 4 or 5 shooters in the bunch. I found it refreshing that none of these appears to need to be culled.
At 60 yards the group location was still right one, but it did widen to a bit more than normal. There was about a 15 mile per hour wind that may have been influencing them at this distance.
Overall, I was very impressed with how these cheap carbons flew when spine-tuned. This test was certainly not conclusive of anything, but it did give me reason for optimism. I'll be shooting these a lot over the next couple weeks (before the season opens), to try and determine if these were just better than normal arrows for a Gold Tip Hunter, or if the spine tester will prove to be very useful.
I asked for input on what an acceptable spine variance would be, and didn't get an answer yet, so I decided to test some of the arrows that had more variance than the others. I choose five arrows where the weakest and strongest sides were between .008 and .015 difference. I have no idea if this falls in a good or bad range, but I figured these were no better than average for a dozen GT hunters. Out of the dozen, there were 6 other arrows that measured more consistant than these and one that measured much worse.
After testing with the spine tester, I marked the weak side of each arrow and placed the cock fletch on that mark. I used 4" feathers attached with a helical clamp. Draw weight was 65 lbs out of a hybrid cam bow. Draw length was 28.5" and arrow length was 28.75". The bow was well-tuned and shooting field tips very well if I did my part. A whisker biscut was used as the rest. A mechanical release was used. I shot the 5 arrows with the Stingers attached, at broadhead targets set at 20, 40 and 60 yards. The arrows were shot one at a time and then marked. I wanted to determine group size and location without actually shooting a group. A total of 3 groups were shot at each distance and averaged to determine group size and location.
To start, no tuning adjustments were made and the sight was not adjusted. At 20 and 40 yards I could tell no difference in group location between these arrow and my field tipped arrows. The sight needed absolutely no adjustment and no tuning adjustments were made either. The group size at these distances was actually a bit smaller than my normal field tip group. It is likely I was just having a good day shooting, but all five arrows flew nicely into the group. Normally, I'd shoot a dozen, culling them down to the best 4 or 5 shooters in the bunch. I found it refreshing that none of these appears to need to be culled.
At 60 yards the group location was still right one, but it did widen to a bit more than normal. There was about a 15 mile per hour wind that may have been influencing them at this distance.
Overall, I was very impressed with how these cheap carbons flew when spine-tuned. This test was certainly not conclusive of anything, but it did give me reason for optimism. I'll be shooting these a lot over the next couple weeks (before the season opens), to try and determine if these were just better than normal arrows for a Gold Tip Hunter, or if the spine tester will prove to be very useful.
#2
Join Date: Feb 2003
Location: Baltimore Maryland USA
Posts: 1,385

I see that you decided to use an over-spined arrow. Was there a reason for this?
Did you spin-test your arrows? Did you cut some lenght off the nock end before you cut-to-length? Did you check the arrows for consistent weight?
Did you use a Hooter Shooter? Are you going to test again on a non-windy day?
Do you plan to test other arrows?
Just a few questions that crossed my mind.
Did you spin-test your arrows? Did you cut some lenght off the nock end before you cut-to-length? Did you check the arrows for consistent weight?
Did you use a Hooter Shooter? Are you going to test again on a non-windy day?
Do you plan to test other arrows?
Just a few questions that crossed my mind.

#3
Thread Starter
Join Date: Feb 2003
Location:
Posts: 2,413

I see that you decided to use an over-spined arrow. Was there a reason for this?
Did you spin-test your arrows?
Did you cut some lenght off the nock end before you cut-to-length?
Did you check the arrows for consistent weight?
Did you use a Hooter Shooter?
Are you going to test again on a non-windy day?

Do you plan to test other arrows?
Just a few questions that crossed my mind.
#4
Join Date: Sep 2004
Location:
Posts: 69

Thanks for the info Straight! It is very nice to get some factual data that is not from the companies. Even with variables that may curb results, your test show valuable information for use in the real enviroment. We can do all we want in a stable enviroment, but without testing in the real world also, we will see a new world in the field. I agree base data from controlled tests would be nice for comparison, but the data you presented is very helpful. Base data we can normally get from a company with a small curve.
Stryker777
Stryker777
#5
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175

After testing with the spine tester, I marked the weak side of each arrow and placed the cock fletch on that mark.

#6
Thread Starter
Join Date: Feb 2003
Location:
Posts: 2,413

I do the same thing, only I align my cock feather over the stiffest axis of the shaft.
#9
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175

Not to speak for Art, but he has to duct tape two arrows together to get his draw length...

Straightarrow, the worst I've gotten has been .035 variance. But I've only gotten that on one arrow out of the dozens I've checked. Tossing it out as an abberration, the average has been around .012 or so. Still about a 5 pound spine difference from one axis of the shaft to the next. Really critical if you're on the very top edge of an arrow's spine rating!
That's a big reason why so many people recommend jumping up to the next stiffest size if you're right on the edge - whether they know that's the reason or not is questionable though. I have to admit I didn't know it, until I got my spine tester and gave it some serious thought.

#10
Thread Starter
Join Date: Feb 2003
Location:
Posts: 2,413

Your results are amazingly similar to mine. I came to the same conclusion with the stiffer arrows. When you're spinning the arrows on the tester and seeing one at .340 and another at .325 or even .315, it becomes very obvious that in a borderline spine situation, the weaker ones are not going to fly the same way the strong ones will. It makes good sense that they should all be strong.
I've been shooting these for a few days now, and even with broadheads, I am still getting groups that are smaller than what I would normally get with field tips on the same arrows. I did get to shoot on a day with little or no wind and my 60 yards groups were very good (for me).
I've been shooting these for a few days now, and even with broadheads, I am still getting groups that are smaller than what I would normally get with field tips on the same arrows. I did get to shoot on a day with little or no wind and my 60 yards groups were very good (for me).